It has drawn criticism from insurers who say gender exerts a strong influence over how likely a person is to claim, and should be reflected in the premiums they pay.

Insurers could try to sidestep the ban by basing their pricing on proxy gender indicators such as the customer's profession or model of car, although this would be vulnerable to legal challenges, law firm Eversheds said.

The ban was also expected to boost demand for so-called telematics insurance, where insurers monitor customers' behaviour through devices installed in cars, and charge according to how riskily they drive, irrespective of gender.